Slab flattening problem

[Anonymous]

I have an annoying problem, I'm not sure whether it's a bug or not. My slab on the 1st floor is flattening every time I change its reference plane location from bottom to top. There are no walls to cover it up, almost the whole slab disappears leaving only the top layer visible. It looks like that in 3d window as well. Any ideas how to solve this?

[Laszlo Nagy]

Is your Section set to Auto-rebuild or Manual Rebuild?
I think it should automatically update after a change if it is set to Auto-rebuild.